A Fire Weather Watch has been issued for the Stanislaus National Forest and the southern Mother Lode from 1000 to 3000 feet, from Wednesday afternoon through Wednesday evening.
The southern Mother Lode includes Tuolumne and Calaveras counties.
Thunderstorms with substanial lightning are expected to develop Wednesday afternoon into Wednesday evening. The storms could start out dry but are expected to be wet by mid afternoon.
The storms will begin in the Sierra Nevada but are expected to extend over the Mother Lode by Wednesday evening.
Lightning strikes may create new fire starts. Dry conditions and locally gusty winds up to 35 mph (near thunderstorm activity) could cause any fire that develops to spread rapidly.
Thunderstoms and showers could linger over the Sierra into early Thursday.
According to the National Weather Service, Thursday (the Fourth of July) and Friday may see an even better chance for thunderstorm activity.
Isolated thunderstorms are also expected over the Sierra Nevada today.
Thunderstorms can produce dangerous cloud-to-ground lightning along with strong gusty winds, brief heavy rain and hail.
If you have outdoor plans this week in the Sierra Nevada, be prepared. Campers, hikers and boaters should keep an eye on the sky and if threatening weather approaches, seek safe shelter or harbor.
The Excessive Heat Warning for the Northern San Joaquin Valley, the Mother Lode and the Sierra Nevada below 4500 feet has been extended through Thursday 8 PM.
High temperatures from the central valley to the Sierra Nevada (including Yosemite Valley) range from 100 to 115. Overnight lows in the central valley and the Mother Lode range from the seventies to the low eighties.
Children, the elderly and people with chronic ailments are the most susceptible to heat-related illness. Heat exhaustion, cramps or in extreme cases heat stroke can result from prolonged exposure to these conditions. Pets and livestock are also vulnerable to heat illness and should be cared for properly.
Remember to drink plenty of fluids, stay in an air-conditioned rooom, stay out of the sun, check up on relatives and neighbors who might need assistance and reduce outdoor exposure.